I was in an emotionally abusive relationship at one point and I will say that leaving was both the hardest and most rewarding thing I have ever done. I'm wanna post here as future you lol to tell you that leaving was like exchanging was a permanent, gutteral deep pain for the sharp pain of what it will mean to heal and move on. The sharp pain is temporary. The dull pain is forever, so keep that in mind.
The first thing I want you to know is that emotional abuse is literally addictive like a drug. The mistreatment gives you a low, the over the top niceness gives you a high. That high is particularly strong because of the wound from the maltreatment so it makes you become addicted to the highs, even though they come at the expense of the lows. When you're craving that addictive love, remind yourself that this is just a craving for an addiction and look into coping mechanisms that would work for quitting alcohol etc.
Leaving is the best thing that you can do!! I remember the day at it's worst was when I was crying because I hated myself. I thought I was fat and ugly and that he would leave me for one of his back burner girlfriends. Luckily I hadn't been there too long but normally quite like myself lol so I knew something was very wrong. That's all I had to go on but it was enough for me to be like, I don't know what's wrong but I USED to be happy and I no longer like myself and that's a problem.
A perfect storm of circumstances (great job offer in another province) got me out of there but it hurt like hell. 7 years later, leaving is the BEST THING THAT EVER HAPPENED TO ME. Yes it was painful. Yes it was hard. But it was worth it because once I fully kicked the addiction I could see so clearly how awful it was. I also think I would have healed a lot faster if I found a trauma informed therapist because I did all this without even knowing I was living in abuse so I recommend doing that asap if you haven't. Even if it's expensive, eat the cost so you can find some guidance because that get you out of being so lost faster. If you're in it now and you feel like it's abuse, it's probably a lot worse because in the moment I barely knew I was being abused. Something about the highs and lows was changing my brain and I luckily got it at the change before I was fully controllable by him. I witness it in other people now, their inability to see that they're being manipulated, and I realize how little I was able to see when I was in it myself. My best advice is RUN.
You deserve a partnership where someone loves you without also harming you. You don't need to stay with someone whose love comes attached to a knife.